Method for manufacturing insert molded products with flexible printed circuit boards, and insert molded products with flexible printed circuit boards

Abstract

To provide a method for manufacturing an insert molded product having a flexible printed circuit board capable of suppressing the formation of long burrs along both sides of the flexible printed circuit board, and an insert molded product having a flexible printed circuit board.SOLUTION: A method for manufacturing an insert molded product has: an arrangement step of arranging an FPC 100 into a mold 300 having a lower mold 310 and an upper mold 320; and a molding step of molding a molded product after filling a cavity CV of the mold 300 with a molding material. The method is characterized in that burr suppression projections 101 are provided on both sides in a width direction of the FPC 100 to restrict the progression of a material leaking from the cavity CV during the molding step, and the burr suppression projections 101 are arranged within the mold 300.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a method for manufacturing an insert-molded product having a flexible printed wiring board, and to an insert-molded product having a flexible printed wiring board. [Background technology]

[0002] Conventionally, insert-molded products have been known that include a flexible printed circuit board (hereinafter referred to as "FPC") and a molded product (such as a gasket) that is integrally formed with the FPC. These insert-molded products can be obtained by insert molding the FPC as an insert component. In such insert-molded products, burrs tend to form near both sides of the FPC in the width direction. The reason for this will be explained with reference to FIG. 5. FIG. 5(a) is a plan view of the insert-molded product near the molded product, and FIG. 5(b) is a schematic cross-sectional view of a mold used in insert molding. The cross-section of the FPC in FIG. 5(b) corresponds to the DD cross-section in FIG. 5(a).

[0003] The insert-molded product 500 includes an FPC 510 and a molded product 520 that is integral with the FPC 510. A mold 600 for insert molding includes a lower mold 610 and an upper mold 620. When performing insert molding, the FPC 510 is placed in the mold 600, and molding material is filled into a cavity (not shown) of the mold 600, and then molding is performed. The insert molding is performed with both sides of the FPC 510 sandwiched between the lower mold 610 and the upper mold 620 across the cavity.

[0004] Here, the FPC 510 generally has a conductor layer functioning as a circuit near the center of its width, but no conductor layer near both sides in the width direction. Therefore, the FPC 510 is generally thinner on both sides than near the center in the width direction. Furthermore, a clearance is provided between the FPC 510 and the mold at the location where the FPC 510 is placed. For these reasons, gaps S0 (shown in black in FIG. 5( b)) are likely to occur near both sides of the FPC 510 in the width direction within the mold 600. Therefore, during molding, molding material leaks from the cavity into the gap S0, resulting in burrs X on both sides of the FPC 510 in the width direction. These burrs X are formed so as to extend along both sides of the FPC 510. If the burrs X become too long, post-processing to remove them may be required for quality reasons. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 5354281 Summary of the Invention [Problem to be solved by the invention]

[0006] An object of the present invention is to provide a method for manufacturing an insert-molded product having a flexible printed wiring board that can prevent burrs from extending long along both sides of the flexible printed wiring board, and an insert-molded product having a flexible printed wiring board. [Means for solving the problem]

[0007] The present invention employs the following means to solve the above problems.

[0008] That is, a method for producing an insert molding having a flexible printed wiring board according to the present invention teeth, a placement step of placing the flexible printed wiring board in a mold having a lower mold and an upper mold; a molding step of filling a molding material into the cavity of the mold and then molding a molded product; A method for manufacturing an insert molded product having A burr suppression protrusion is provided on each side of the width of the flexible printed wiring board to restrict the progress of material leaking from the cavity during the molding process, and the burr suppression protrusion is arranged within the mold.

[0009] According to the present invention, the burr suppressing protrusions can prevent burrs from extending long along both sides of the flexible printed wiring board.

[0010] a gap is provided between a side surface of a portion of the lower mold where the burr suppression protrusion is disposed and the burr suppression protrusion, The upper mold may be provided with a pressing protrusion that presses and compresses the burr suppression protrusion to reduce the gap.

[0011] This makes it possible to prevent the molding material from getting around to the tip end side of the burr suppressing protrusion.

[0012] Preferably, no metal foil is provided inside the burr suppression protrusion.

[0013] This makes it easier for the burr suppressing protrusion to expand when the pressing protrusion presses and compresses the burr suppressing protrusion, thereby making it possible to more reliably reduce the gap.

[0014] The insert molding product having the flexible printed wiring board of the present invention is An insert molded product obtained by molding a molded product using a flexible printed wiring board as an insert part, The flexible printed wiring board is characterized in that it is provided with burr suppression protrusions on both sides of its width that restrict the progress of material leaking out of the mold cavity when the molded product is formed.

[0015] According to the present invention, the burr suppressing protrusions can prevent burrs from extending long along both sides of the flexible printed wiring board.

[0016] The burr suppression protrusions may be provided on both sides of the molded product.

[0017] Preferably, no metal foil is provided inside the burr suppression protrusion.

[0018] The above configurations may be combined as much as possible. [Effects of the Invention]

[0019] As described above, according to the present invention, it is possible to prevent burrs from extending long along both sides of a flexible printed wiring board. [Brief explanation of the drawings]

[0020] [Figure 1] FIG. 1 is a schematic diagram of an insert molding according to an embodiment of the present invention. [Figure 2] FIG. 2 is an explanatory diagram of insert molding according to an embodiment of the present invention. [Figure 3] FIG. 3 is an explanatory diagram of insert molding according to an embodiment of the present invention. [Figure 4] FIG. 4 is a diagram showing a modified example of the flexible printed wiring board according to the embodiment of the present invention. [Figure 5] FIG. 5 is a schematic diagram of a conventional insert-molded product. DETAILED DESCRIPTION OF THE INVENTION

[0021] The following detailed description of the present invention will be given by way of example with reference to the accompanying drawings, although the dimensions, materials, shapes, relative positions, etc. of the components described in the examples are not intended to limit the scope of the present invention unless otherwise specified.

[0022] (Example) 1 to 3, a method for manufacturing an insert-molded product having a flexible printed wiring board according to an embodiment of the present invention, and an insert-molded product having a flexible printed wiring board will be described. FIG. 1 is a schematic diagram of an insert-molded product according to an embodiment of the present invention. FIG. 1(a) is a plan view showing the vicinity of the insert-molded product, and FIG. 1(b) is a schematic cross-sectional view of the insert-molded product (cross-sectional view taken along line AA in FIG. 1(a)). FIG. 2 is an explanatory diagram of insert molding according to an embodiment of the present invention. FIG. 2(a) is a plan view showing the state after mold clamping, and the mold is shown in perspective with dotted lines to make the internal state easier to understand. FIG. 2(b) is a cross-sectional view taken along line BB in FIG. 2(a). FIG. 3 is an explanatory diagram of insert molding according to an embodiment of the present invention. FIG. 3(a) is a schematic cross-sectional view of the mold before mold clamping, and FIG. 3(b) is a schematic cross-sectional view of the mold after mold clamping. FIG. 3(b) is a cross-sectional view taken along line CC in FIG. 2(a).

[0023] <Insert molding> The configuration of an insert-molded product 10 according to this embodiment will be described with particular reference to Fig. 1. The insert-molded product 10 includes a flexible printed wiring board (hereinafter referred to as "FPC 100") and a gasket 200 as a molded product that is integrally provided with the FPC 100. The gasket 200 is provided integrally with the FPC 100 by insert molding the FPC 100 as an insert component. Note that in this embodiment, a gasket is used as an example of a molded product, but the molded product according to the present invention is not limited to a gasket.

[0024] The FPC 100 includes a base film 110, a plurality of conductor layers 120 that are provided on the base film 110 and formed by etching a metal foil (such as copper foil), and a cover film 130 that covers the plurality of conductor layers 120. The cover film 130 is fixed to the base film 110 and the conductor layers 120 by an adhesive 140 after the conductor layers 120 are formed. The conductor layers 120 function as circuits (wiring). The base film 110 and the cover film 130 are made of a resin film such as a polyimide film.

[0025] In the FPC 100 according to this embodiment, burr suppression protrusions 101 are provided on both sides in the width direction, on both sides of the gasket 200, to restrict the progress of material leaking from the cavity CV of the mold 300 when molding the gasket 200. No conductor layer 120, which is a metal foil, is provided inside the burr suppression protrusions 101.

[0026] <Manufacturing method for insert molding products> 2 and 3, a method for manufacturing the insert-molded product 10 according to this embodiment will be described. The mold 300 used for insert molding comprises a lower mold 310 and an upper mold 320. A cavity CV is provided by engraved portions formed in the lower mold 310 and the upper mold 320, respectively. The FPC 100 is placed in the mold 300 configured in this manner (placement process). In this embodiment, grooves 311 for fitting the FPC 100 are provided on both sides of the engraved portion for forming the cavity CV in the lower mold 310. By fitting the FPC 100 into these grooves 311, the FPC 100 is placed in a predetermined position within the mold 300. In the FPC 100, the conductor layer 120 is provided near the center in the width direction inside the FPC 100, and the conductor layer 120 is not provided near both sides in the width direction. As a result, as explained in the background art, the thickness of the FPC 100 is thinner on both sides than near the center in the width direction, and gaps S0 are likely to occur near both sides in the width direction of the FPC 100 within the mold 300.

[0027] When the FPC 100 is placed in the mold 300, the burr suppression protrusion 101 is disposed within the mold 300. Before the mold is closed, a gap SX is provided between the burr suppression protrusion 101 and the side surface of the groove 311, where the burr suppression protrusion 101 is disposed, of the lower mold 310 (see FIG. 3(a)). The upper mold 320 is provided with a pressing protrusion 321 that presses and compresses the burr suppression protrusion 101. When the mold is closed, the pressing protrusion 321 compresses and presses the burr suppression protrusion 101, causing the burr suppression protrusion 101 to expand in a direction perpendicular to the compression direction (see the arrow in FIG. 3(c)), thereby reducing the gap SX. It is desirable to set the materials and dimensions of each part so that this gap SX is 0.01 mm or less. Note that the conductor layer 120, which is a metal foil, is not provided inside the burr suppression protrusion 101, and therefore, expansion during compression is not suppressed.

[0028] After the mold is clamped, similar to general insert molding, the cavity CV of the mold 300 is filled with a molding material, and then the gasket 200 is molded (molding process). As the material for the gasket 200, for example, a rubber material such as EPDM or silicone rubber is applied, and a thermoplastic resin can also be used.

[0029] Although the dimensions of each component are not particularly limited, an example will be described below. As shown in FIG. 1, the distance S1 from the gasket 200 to the burr-suppressing protrusion 101 can be set to 1.2 mm. The width S2 of the burr-suppressing protrusion 101 can be set to 2.25 mm. The protrusion width S3 of the burr-suppressing protrusion 101 can be set to 1.5 mm. The thickness T1 of the FPC 100 near the conductor layer 120 can be set to 0.26 mm. The thickness T2 of the burr-suppressing protrusion 101 can be set to 0.2 mm. With the above settings, the width S4 (see FIG. 3(c)) of the portion where the burr-suppressing protrusion 101 is pressed by the pressing protrusion 321 can be set to approximately 0.5 mm from the tip of the burr-suppressing protrusion 101. With the above settings, the gap SX can be reduced to 0.01 mm or less by compressing the burr-suppressing protrusion 101 by approximately 0.06 mm.

[0030] <Modification> Although the burr suppressing protrusion 101 shown in the above embodiment has a rectangular planar shape, the shape of the burr suppressing protrusion 101 is not limited thereto. For example, as shown in FIG. 4(a), a burr suppressing protrusion 101a having a planar shape in which a large rectangle and a small rectangle are connected with a step can be used. Also, as shown in FIG. 4(b), a burr suppressing protrusion 101b having a semicircular planar shape can be used, and as shown in FIG. 4(c), a burr suppressing protrusion 101c having a triangular planar shape can be used. Furthermore, as shown in FIG. 4(d), a portion or all of the burr suppressing protrusion 101 can be cut off after the gasket 200 is molded. Note that C in FIG. 4(d) indicates a cutting line. Furthermore, while the above embodiment shows a single-sided FPC, a double-sided FPC can also be used, as shown in FIG. 4(e). That is, in this FPC 100A, a conductor layer 120 and a cover film 130 are provided on both sides of a base film 110. Although not specifically shown, a multi-layer FPC having more films and conductor layers can also be used.

[0031] <Method for manufacturing an insert molded product according to this embodiment and advantages of the insert molded product> According to this embodiment, the burr suppression protrusion 101 can prevent burrs from extending long along both sides of the FPC 100. That is, as shown in Fig. 2(a) which is an enlarged view of a portion near the burr suppression protrusion 101, even if material leaks out of the gap S0 during molding, the burr suppression protrusion 101 restricts the material from progressing as indicated by the arrow D. Therefore, the burrs can be prevented from extending long.

[0032] In this embodiment, the pressure projection 321 provided on the upper mold 320 presses and compresses the burr suppression projection 101 during mold clamping, thereby reducing the gap SX. This prevents the molding material from getting around the tip of the burr suppression projection 101, further reducing the length of the burr. Furthermore, since the conductor layer 120, which is a metal foil, is not provided inside the burr suppression projection 101, the burr suppression projection 101 is more likely to expand when pressed and compressed by the pressure projection 321, thereby more reliably reducing the gap SX.

[0033] In this embodiment, the burr suppression protrusions are provided on both sides of the molded product (gasket 200 in this embodiment). However, if the formation of long burrs on one side of the molded product does not affect the quality, a configuration in which the burr suppression protrusions are provided on only one side of the molded product can be adopted. Also, in this embodiment, a configuration in which a conductive layer is not provided inside the burr suppression protrusions is shown. However, even if a conductive layer is provided inside the burr suppression protrusions, a certain degree of effect can be obtained. [Explanation of symbols]

[0034] 10: Insert molding 100,100A:FPC 101, 101a, 101b, 101c: Burr suppression protrusion 110: Base film 120: Conductor layer 130: Cover film 140: Adhesive 200: Gasket 300: Mold 310: Lower mold 311: Groove 320: Upper mold 321: Pressing protrusion CV: Cavity

Claims

1. a placement step of placing the flexible printed wiring board in a mold having a lower mold and an upper mold; a molding step of filling a molding material into the cavity of the mold and then molding a molded product; A method for manufacturing an insert molded product having A method for manufacturing an insert-molded product having a flexible printed wiring board, characterized in that burr-suppressing protrusions that restrict the progress of material leaking from the cavity during the molding process are provided on both sides of the flexible printed wiring board in the width direction, and the burr-suppressing protrusions are arranged within the mold.

2. a gap is provided between a side surface of a portion of the lower mold where the burr suppression protrusion is disposed and the burr suppression protrusion, 2. The method for manufacturing an insert-molded product having a flexible printed wiring board according to claim 1, characterized in that the upper mold is provided with a pressing protrusion that compresses the burr suppression protrusion to reduce the gap.

3. 3. The method for manufacturing an insert-molded product having a flexible printed wiring board according to claim 1, wherein no metal foil is provided inside the burr suppression protrusion.

4. An insert molded product obtained by molding a molded product using a flexible printed wiring board as an insert part, An insert-molded product having a flexible printed wiring board, characterized in that the flexible printed wiring board is provided with burr-suppressing protrusions on both sides in the width direction, which restrict the progress of material leaking out of the cavity of the mold when the molded product is formed.

5. 5. The insert-molded product having a flexible printed wiring board according to claim 4, wherein the burr suppression protrusions are provided on both sides of the molded product.

6. 6. The insert-molded product having a flexible printed wiring board according to claim 4, wherein no metal foil is provided inside the burr suppression protrusion.

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